The present invention relates to an apparatus for the deposition and preshaping of a band section in a shaping mould which is provided in a thermal shaping station for containers incorporated in a packing machine and which has a base supported on a machine frame which is able to move relative to a moulding unit having at least one shaping cavity defined by the inner side walls of the mould, said unit being vertically movable between an upper position, called the thermal shaping position and a lower position, called the container discharge position, said apparatus being of the type comprising a transfer member such as a plunger equipped with a control rod and mounted in sliding manner, preferably without a significant lateral tolerance, in a cylindrical cavity, called a prewinding cavity, of a band section prewinding unit, said prewinding cavity being open at least towards the moulding unit and is operated in such a way that it receives a band section and is fixed in such a way that it is preferably located below and in the immediate vicinity of the discharge position from the moulding unit and aligned with the said shaping cavity which, at its lower end has an inner shoulder extending perpendicularly to the axis and towards the inside of the shaping cavity and at the most up to the extension of the prewinding cavity, the base of the mould comprising a base plate which is supported on the machine frame via a supporting rod and whose dimensions are such that the side walls can engage without a significant lateral clearance in the base opening defined by the said internal shoulder.
Such an apparatus is in part known from French Patent 2,034,915. In a prewinding cavity, the said apparatus uses a transfer plunger which drives the band section into the shaping cavity when the latter is aligned with the said prewinding cavity. Shaping cavities are also known which are located in a moulding unit and whose bases are constituted by base plates supported on a frame, the moulding unit being movable relative to said base plates between an upper or shaping position and a lower or discharge position (cf French Pat. No. 2,051,643). Moulding units are also known which are movable relative to base plates supported on a machine frame and whose end has prewinding cavities (cf French Patent Application 2,256,013), the shaping cavities of the moulding units being provided at their lower end with internal shoulders. As a result of their design, none of the known apparatuses or the combination of certain components of said apparatuses permits the application of the band section against the internal side walls of each shaping cavity and more particularly against the wall portions having a small radius of curvature and to maintain them in this position until moulding thereon has taken place by the thermoplastic material constituting the container to be shaped.